1 class Operation():
2
3 def __init__(self, NumberA=0, NumberB=0):
4 self.NumberA = NumberA
5 self.NumberB = NumberB
6
7 def GetResult(self):
8 pass
9
10
11 class AddOp(Operation):
12
13 def GetResult(self):
14 return self.NumberB + self.NumberA
15
16
17 class MinusOp(Operation):
18
19 def GetResult(self):
20 return self.NumberA - self.NumberB
21
22
23 class MultiOp(Operation):
24
25 def GetResult(self):
26 return self.NumberA * self.NumberB
27
28
29 class DivideOp(Operation):
30
31 def GetResult(self):
32 try:
33 return 1.0 * self.NumberA / self.NumberB
34 except ZeroDivisionError:
35 raise
36
37
38 class OperationFatory():
39
40 def ChooseOperation(self, op):
41 if op == '+':
42 return AddOp()
43 if op == '-':
44 return MinusOp()
45 if op == '*':
46 return MultiOp()
47 if op == '/':
48 return DivideOp()
49
50
51 if __name__ == '__main__':
52 ch = ''
53 while not ch == 'q':
54 NumberA = float(input('Please input number1: '))
55 op = input('Please input the operation: ')
56 NumberB = float(input('Please input number2: '))
57 OPFactory = OperationFatory()
58 OPType = OPFactory.ChooseOperation(op)
59 OPType.NumberA = NumberA
60 OPType.NumberB = NumberB
61 print('The result is:', OPType.GetResult())
62 print('\n#-- input q to exit any key to continue')
63 try:
64 ch = input()
65 except:
66 ch = ''
